The field of this invention relates to a clip for holding sheet material, and while same may have various other applications, it has been particularly designed to hold such sheet material as elongated strips of photographic films.
As is well known to those skilled in the art, an immense number of photographic films after being developed, fixed and washed, are suspended for drying. The film is commonly held suspended from a film clip which engages the upper end of the film. And it is also common practice to have a weight connected to the lower end of the film by a film clip to hold the film steady and in a vertical position.
Film clips have been previously known and are normally fabricated from sheet metal and engage the film by either piercing the film or by tightly clamping the film. These clamping and piercing devices frequently grasp the film in the photographic sensitive area or impose a warping tendency on the film in the immediate area of the clamping or the piercing.
It is also common that some prior art film clips are fabricated from corrosive materials. The corrosiveness of the materials is undesirable since the corrosiveness results in rust caused by the photographic developing chemicals with the rust then contaminating the photographic film which then appear on the processed film.
In the past it has been attempted to eliminate the rust problem by electroplating the clip with a non-corrosive metal. However, the inherent porosity of the electroplating metal is such that the corrosion is only delayed rather than being prevented and ultimately rust streaks again appear on the processed films.
Also, in the prior art type of film clip which grips rather than pierces the film tends to lose their gripping ability as a result of the lubricating properties of the processing fluids. This results in the film being dropped to the bottom of the processing tank which if not retrieved immediately will result in destroying of the film.